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Toxicity to aquatic algae and cyanobacteria

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Description of key information

There is a high probability that the product is not acutely toxic to aquatic algae. 

Key value for chemical safety assessment

Additional information

The toxicity of disodium (sulphonatothio)acetate; dried to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD 201 (2011). The aim of the study (BASF SE, 2015) was to assess the effects on the growth rate over a period of 72 hours. In this aquatic test, the original liquid product was tested. This product contains 39.3 % dry content, which is identical with the test item "Disodium (sulphonatothio)acetate; dried". This dry content contains 75% of the chemical disodium (sulphonatothio) acetate.

The results of the toxicity test are reported based on the dry content. Additionally, the results are given for the liquid product.

A water solubility of 557 ± 24 g/L at 20.0 °C ± 0.5 °C was determined with the dried product and refers to the dry content. The stock solution, identical with the test solution, of 509 mg/L of the liquid product was freshly prepared with dilution water before the start of exposure (at 0 hours) in a measuring flask and agitated gently until the solution was clear. The limit concentration remained visually clear throughout the exposure period. The study was conducted under static conditions with an initial cell density of 6153 cells/mL. The toxicity of a solution with a nominal test item concentration of 509 mg/L - corresponding to 200 mg test item dry content/L - was assessed in a limit test. Six replicates were tested for the test item concentration and for the control, respectively. The environmental conditions were within the acceptable limits.

The limit test concentration of disodium (sulphonatothio)acetate; dried and the control was analytically verified by LC-MS/MS at the start and the end of exposure. The measured concentration of disodium (sulphonatothio)acetate; dried at the start of exposure was 108 % of the nominal test item concentration. At the end of exposure, the measured concentration was 94 % of the nominal test item concentration. Therefore all effect values are based on the nominal test item dry content concentration of the test item.

Based on the nominal dry content of the test item disodium (sulphonatothio)acetate; dried, the NOEC, the ErC10 and the ErC50 after 72 hours were determined to be greater than 200 mg/L. Based on the nominal concentrations of the liquid test item (containing 39.3% dry content) disodium (sulphonatothio)acetate; dried the NOEC, the ErC10 and the ErC50 after 72 hours were determined to be greater than 509 mg/L.